It is known in the art to visualize structures inside an object of interest by means of, for example, X-ray radiation. Such a visualization is available without the need of opening the object of interest, i.e. cutting or injuring or damaging or even destroying the object. Depending on the angle of radiation, the structures will be projected and, thus, seen only from one side.
Further known techniques provide the possibility of generating a 3D volume image of an object of interest, wherein, firstly, the object will be radiated from different point of views, i.e. different radiation angles, and, secondly, a 3D volume image is reconstructed on the basis of the different projections.
In the field of medical applications, angiography is used to detect a modification, i.e. a lesion or narrowing in a vascular bed by using a cardiovascular X-ray system to take images of the vessels during intra-arterial injection of a contrast material.
In order to get a proper assessment of a lesion, the orientation (rotation and angulation) of the X-ray system is critical.
Currently “Foreshortening Optimal Viewmaps” are used in cardiovascular X-ray systems and assist in determining the X-ray system orientation that will image the lesion with minimum foreshortening of the vessel length in the projection image. The optimal viewmap is based on 3D centerline geometry of the vessels that can be derived from e.g. 3D CT data or 3D Rotation Angiography data. The optimal viewmap is a map depicting average foreshortening of a selected vessel segment as a function of the X-ray system rotation and angulation. The Optimal Viewmap does not take the shape of the cross-section of the vessel into account.
In clinical reality, the cross section of the lesions is frequently asymmetric. For clinical purposes it is crucial to find an X-ray view that gives a projection image where the minimum luminal cross section of the lesion is shown. Depending on the X-ray view the diameter of the vessel in the projection image will appear differently for an asymmetric lesion. Finding the projection image with the minimum lesion diameter is crucial because treatment decision (to stent or not) are based on the procedural reduction in diameter as seen on the 2D projection image. For asymmetric lesions, depending on the X-ray view the diameter reduction may seem less severe than in reality leading to incorrect treatment decisions.